Raid Lockout Question

Essentially, our raid team is somewhat divided at the moment on whether to continue full clearing SoO for the chance at heirlooms or just work full-time on Heroics.

Now a potential solution we came up with was to clear up to Paragons of the Klaxxi, bring a few alts in for that fight, then switch back to mains, leaving us with 2-3 alts all with saves at Garrosh which we can then use in future weeks to skip up to him.

However...I do know that Heroic raid IDs do work differently, will killing some of the earlier bosses on Heroic cause the lockout to become invalid after we kill Garrosh?

Steps in order:

1. Clear whatever heroics we can.
2. Once we reach NORMAL Paragons, bring in 2-3 alts.
3. Switch back to mains and kill Garrosh.
NEXT WEEK:
1. Clear whatever heroics we can.
2. Last 30 minutes of the week, bring one of the saved alts in, extend lock to garrosh and kill.